Flow divider



Jan. 2, 1962 H. McCOMBS, JR 3,01

FLOW DIVIDER Filed Oct. 7, 1958 2 Sheets-Sheet 1 INVENTOR.

How/41w L M? COMES- a gmfm A T TOR/VEY.

Jan. 2, 1962 H. 1.. MOCOMBS, JR 3,015,338

FLOW DIVIDER Filed Oct. 7, 1958 2 Sheets-Sheet 2 \2 v m g g INVENTOR.

HOWARD L MF'COMBSJR ATTORNEY.

United States Patent 3,015,338 FLOW DIVIDER Howard L. McCombs, Jr., South Bend, Ind., assignor to The Bendix Corporation, a corporation of Delaware Filed Oct. 7, 1958, Ser. No. 765,782 5 Claims. (Cl. 137-100) The present invention relates to a flow divider for dividing flow from a common source for discharge from two outlets in equal quantities irrespective of differences between the outlet pressures.

The flow divider of the present invention is particularly useful in a fuel injection system of the type disclosed and claimed in US. Patent No. 2,447,268 wherein a single master control supplies fuel to two injection pumps. The output of the injection pumps is regulated by a diaphragm controlled member in each pump which is positioned as a function of the fuel pressure acting on the diaphragm. The force required to position the diaphragm control member Varies with pump tolerances, dirt, spring rates,

pump speed, etc. in a manner which i difficult or impossible to determine or predict. In the past a synchronizing bar has been provided to connect the diaphragm control members of pairs of injection pumps to insure equal outputs therefrom. The synchronizing bar is not, however, without its problems and has in some instances proved difficult to maintain in calibration due to engine heat, vibration, etc. It is an object of the present invention to provide a flow divider for a fuel injection system which will eliminate the need for a synchronizing bar and which will divide the flow from a common source, such as in a fuel injection master control to a pair of injection pumps in equal quantities irrespective of the outlet back pressure.

It is another object of the invention to provide a flow divider which will divide flow from a common source into two equal quantities over a relatively large range of flows and with a relatively small pressure drop across the divider.

It is a further object of the invention to provide a flow divider which is simple in construction, accurate and re liable in operation.

These and other objects will become readily apparent from the following detailed description taken in connection with the appended drawings in which:

FIGURE 1 is a diagrammatic view of a fuel injection system provided with a flow divider of the present invention;

FIGURE 2 is a sectional view of a flow divider shown in FIGURE 1.

Referring now to the drawings and more particularly to FIGURE 1, numeral designates a master control having a fuel inlet 12 and a fuel discharge conduit 14 which is connected to a flow divider 16 which is in return respectively connected to fuel injection pumps 18 and 28 by means of conduits 22 and 24. The fuel injection pumps 18 and are provided with a number of discharge lines 26 which respectively terminate with a discharge nozzle 28. The number of nozzles may conveniently correspond to the number of cylindersor combustion chambers of the engine to which the fuel injection system is adapted to supply fuel. The master control 10 is substantially identical to the master control disclosed in US. Patent No. 2,447,268 and functions to receive unrnetered fuel from a suitable supply (not shown) through inlet 12 and to deliver fuel metered in accordance with engine requirements through conduit 14 to the flow divider 16 and thence to the fuel injection pumps 18 and 20 for injection into the engine through nozzles 28. The particular construction of the master control is not important to an understanding of the present invention.

Referring now to FIGURE 2, flow divider 16 is provided with a housing 66 having an inlet 68 connected to conduit 14 and first and second outlet 70 and 72 respectively connected to conduits 24 and 22. Inlet 68 is connected to the first outlet 70 by means of chamber 74 calibrated passage 76, passage 78, chamber and valve 82. Inlet 68 is connected to the second outlet 72 by means of chamber 74 calibrated passage 84, passage 86, chamber 88, and valve 90. The connection between the fuel chamber 74 and the calibrated passages 76 and 84 i controlled by a valve 92 which is formed on one side with a guide stem 93 and on the other side with a stem 94 which in turn is centrally connected to a diaphragm or movable wall 96. Diaphragm 96 is subjected on one side to inlet fuel pressure (P in chamber 74 and on the opposite side to the force of spring 98 and the pressure in passage 78 (P which is connected to a chamber 100 on the opposite side of diaphragm 96 by means of a conduit 102. Valve 92 functions to vary the inlet area of calibrated passages 76 and 84 so as to maintain a substantially constant pressure drop between P pressure and P pressure.

Valve 90 controlling the second outlet 72 is of balanced construction and comprises a stationary slotted bushing 104 carrying a sleeve 106 which is centrally clamped to a diaphragm or movable wall 108. A chamber 110 is formed on the opposite side of diaphragm 188 from the chamber 88 and is connected to P pressure in chamber 80 by means of conduit 112. The pressure P in the discharge conduit 22 is regulated by valve 90 which in turn is regulated by the diaphragm 108 which is responsive to the differential between the P pressure in chamber 88 and P pressure in chamber 110.

The first outlet 70 is controlled by a valve 82 of similar construction to valve 90 and comprises a stationary slotted bushing 116 and a sleeve 118 which is centrally clamped to a diaphragm or movable wall 126. A chamber 122 is formed on the opposite side of diaphragm 120 from the chamber 80 and is connected to the second outlet 72 by means of conduit 124. Valve 82 is positioned by diaphragm 120 which is responsive to the pressure differential between P pressure in chamber 80 and P pressure in chamber 122. A light spring 126 urges valve 82 toward closed position.

In operation valve 92 functions to maintain a predetermined pressure difference between P pressure and P pressure the amount of which is determined by the force of spring 98 and in a specific example may be on the order of 2 p.s.i. Valve 90 is positioned by diaphragm 108 to maintain P pressure in chamber 110 equal to P pressure in chamber 88. Thus with P equal to P and the areas of calibrated passages 76 and 84 equal then the fuel flow through passage 76 will equal the fuel flow through passage 84 since P P =P -P The division of flow through divider will remain equal irrespective of variations between the outlet pressures P and P This can be best illustrated by means of the following examples.

If we assume a condition Where P equals 5 p.s.i. and P equals 10 p.s.i. and spring 98 exerts a force of two pounds on diaphragm 96 then P pressure will assume a value equal to P pressure viz., 10 p.s.i. Since valve 82 is responsive to the difierence in pressure between P pressure and P pressure, valve 82 will be opened to the wide open position. Valve 90 will assume a position to cause P to equal P pressure viz, 10 p.s.i. P pressure of 10 p.s.i. is vented to chamber 100 and together with spring 98 positions valve 92 to cause inlet pressure P to assume a value of 12 p.s.i. If the assumed conditions were reversed e.g. P equal to 10 p.s.i. and P equal to 5 p.s.i. then P pressure which is vented to chamber 122 would cause valve 82 to be positioned to bring P pressure to a value equal to P pressure viz., 10 p.s.i. Valve 90 would be open to the wide open position and P would be equal to P pressure viz., 10 p.s.i. As in the previous example P pressure of 10 p.s.i. vented to chamher 101) together with spring 9% would cause P pressure to assume a value of 12 psi. If we were toassu-me a condition Where both P and P were equal to p.s.i. then valve 82 would be positioned to cause P to equal 10 p.s.i.; and valve 90 would be positioned to cause P to equal P viz., 10 psi. It is to be noted that when the outlet pressures P and P are equal both valves 82 and 90 are effective to regulate flow. However, when the outlet pressures P and P are not equal only the valve 82 or 90 regulating the flow to the lowest pressure is effective and the other valve is wide open. It is also to be noted that P pressure is equal to 'or greater than P pressure and that P is always equal to P The valves 82 and 90 may be so designed with relation to the flow requirements of divider 16 that the pressure drop across the valves is so small as to be negligible. If, however, a pressure drop across valve 90 is experienced of a sufiicient amount to be significant when the valve 90 is in the Wide open position a spring 126 may be utilized-to compensate for the pressure drop.

In a particular embodiment of a fuel injection system the flow through the fuel divider 16 varies from 20 pounds per hour to 2,000 pounds per hour or a 10 to 1 flow range. Experience has shown that a minimum metering head of 1 to 2 psi. across the calibrated passages 76 and 84 is required for accurate metering. Since for a constant area flow path the metering head varies as the square of the flow there would be a 100 to 1 metering head change with a 10 to 1 change in fiow. For the particular example under consideration, this'would require an unnecessarily high inlet pressure. Valve 92 functions to vary the area of the calibrated passages 76 and 84 so as to maintain a substantially constant pressure drop over the entire flow range of the flow divider thereby permitting the use of the lowest possible inlet pressures.

It is to be noted that in the flow divider of the present invention there is no master slave relationship between the valves 90 and 82; either or both of the valves may perform the flow regulating function. In flow dividers utilizing the master slave principle, the slave pressure is either limited so as to never exceed the master pressure or a spring force is provided to increase the pressure on the upstream side of the master valve whereby the slave pressure is permitted to exceed the master pressure by an amountequal to-or less than the spring force. The

, addition of a spring to the master valve increases the pressure drop across the fiow divider and thereby requires the supply pump capacity to be increased which causes the size and/or weight of the pump to increase. In aircraft applications any increase in the size and/or Weight of the supply pump is objectionable. Furthermore in the replacement field wherein the flow divider of the present invention would be substituted for the synchronizing bar the fuel injection supply pumps have insufiicient capacity to accommodate for a pressure drop which would be encountered in a master slave type fuel divider having spring loading on the master valve.

The flow divider of the present invention may be utilized in existing systems and in future systems without requiring changes in the other components of the system.

While I have herein illustrated a preferred embodianeut of my invention it readily will be understood that numerous changes, modifications, and substitutions of equivalents may be made therein Without departing from the spirit and scope of my invention. 7

I claim:

- 1. A flow divider comprising a housing having a fluid inlet and first and second fluid outlets, first and second conduits respectively connecting said inlet to said first and second outlets, valve means controlling the area of the connection between said inlet and said conduits, means responsive to the pressure differential between the pressures in said inlet and one of said conduits for control ing id valve me ns, fir t and second Valves respec- 4 tively controlling said first and second outlets, a movable wall connectedto said first valve and responsive to the pressure diiferential between the pressures in said first conduit and said second outlet, and a movable wall connected to said second valve responsive to the pressure differential between the pressures in said conduits.

2. A flow divider comprising a housing having a fluid inlet and first and second fiuid outlets, first and second conduits respectively connecting said inlet to said first and second outlets, valve means controlling the area of the connection between said inlet and said conduits, a

, movable well connected to said valve means, resilient means urging said wall in a direction to close said valve means, means for subjecting one side of said movable wall to inlet pressure to urge said valve means toward open position, means for subjecting the opposite side of said wall to the pressure in said first conduit to urge said valve toward closed position, first and second valves respectively controlling said first and second outlets, first and second movable walls respectively connected to said first and second valves, means for subjecting one side of said first wall to the pressure in said first conduit to urge said first valve toward open position, means for subjecting the opposite side of said first wall to the pressure in said second outlet to urge said first valve toward closed position, means for subjecting one side of said second Wall to the pressure in said first conduit to urge said second valve toward closed position, and means for subjecting the opposite side of said second wall to the pressure in said second conduit to urge said second valve toward open position.

3. A flow divider as claimed in claim 2 wherein resilient means is provided for urging said first valve toward closed position.

4. A flow divider comprising a housing having an inlet "and first and second outlets, first and second conduits respectively connecting said inlet to said first and second outlets, a calibrated flow restricting portion formed in each of said conduits, said portions being formed with equal areas, first valve means in said first conduit responsive to the diiferential pressure between the presssure in said first conduit downstream of said portion and the pressure in said second outlet for maintaining the pres sure in said first conduit equal to or greater than the pres sure in said second outlet, and second valve means in said second conduit responsive to the differential pressure between the pressures in said first and second conduits do-wn stream of said portions for maintaining the pressure in said second conduit substantially equal to the pressure in said first conduit.

5. A flow divider comprising a housing having a fluid inlet and first and second fluid outlets, first and second conduits respectively connecting said inlet to said first and second outlets, first and second valves respectively controlling said first and second outlets, said conduits each having a calibrated flow restricting portion upstream of said valves, said portions being formed with equal areas, a movable Wall connected to said first valve and responsive to the pressure diflerential between the pressure in said conduit downstream of said calibrated portion and the pressure in said second outlet and a movable wall connected to said second valve responsive to the pressure differential between the pressures in said conduits downstream of said calibrated portions.

References Cited in the file of this patent UNITED STATES PATENTS 353,704 Nash Dec. 7, 1886 2,460,774 Trautman Feb. 1, 1949 2,466,485 Schultz Apr. 5, 1949 2,606,066 Thompson Aug. 5, 1952 2,643,664 Willett June 30, 1953 FOREIGN PATENTS 549,211 Great Britain Nov. 11, 1942 

